The present invention relates in general to apparatus for the replacement of deteriorated underground pipes, and more particularly methods and apparatus for breaking up the old underground pipes and forcing new pipes through the path of the broken pipeline.
Virtually every city in the United States, as well as in foreign countries, employs sanitary drainage systems and sewage disposal systems. A vast network of underground pipes is effective to carry the waste water and sewage to the respective disposal systems. The underground piping systems are generally constructed of concrete, clay or metal pipes which have a lifetime of many years. However, such piping systems do not last indefinitely. There are many external influences which can reduce the lifetime of such piping systems. For example, an accumulation of acids from the formation of hydrogen sulfide gas in the sewer attacks the material in concrete and asbestos cement pipes. The gases condense on the upper internal surface of the pipe and the resulting acids can deteriorate the pipe so that holes are eventually formed through the sidewalls, or the pipe becomes so porous that it is weakened and easily crumbles. While clay tile is generally not affected by the hydrogen sulfide gas or acids, the quality of the clay used to fabricate the clay tile can be of such inferior quality that the life of the pipe is greatly reduced. Metal pipes can be subject to corrosive action and breakage. Further, the sealed ends of any of these types of pipes can become defective over time, thereby allowing roots to grow therein. As the roots grow in size, the pipes become separated and allow sewage or waste water to leak into the surrounding soil. The movement of the soil such as by frost, shifting or earthquakes is another mechanism which can cause leaks in the piping system.
A recent concern of the integrity of the national underground piping systems is that of the environment affected by the piping system. Numerous environmental regulations have been implemented to control the integrity of the underground piping systems to preserve the quality of the water, air and soil. In view of the foregoing, a substantial concern has been generated over the quality of the present underground piping systems throughout the United States, and techniques for replacing the same due to the age or deterioration of the pipes themselves or entire systems.
Various techniques and apparatus have been developed for addressing the problem of replacing underground pipes, and especially sewer pipes. A major concern for the replacement of underground pipes is that of minimizing the disturbance of private or public property in replacing the pipes. For example, while the trenching or digging with a backhoe is effective to expose the old underground pipes for repair or replacement, such technique is extremely invasive and disturbing of the soil owned by the property owners. Furthermore, such replacement techniques are time consuming and thus represent a substantial interruption in the service to the customers using the underground pipes. To circumvent many of these problems, many techniques and devices have been developed for pulling a xe2x80x9cmolexe2x80x9d through the old piping system to break it up and provide a channel through which a new pipe is pulled. U.S. Pat. No. 4,983,071 by Fisk, et al. discloses a pipe bursting apparatus which is pulled through the old pipe to break it up, and new pipe attached to the bursting equipment is simultaneously pulled and thus installed in the path of the old pipe. This system requires a cable to be initially routed through the old pipe system and connected to a conical element for pulling through the old system and bursting the pipe. Connected to the conical element is a new plastic pipe which is pulled by the equipment and automatically routed in the path of the old system. U.S. Pat. No. 5,076,731 by Luksch discloses an element that is pulled through the old piping system to form an enlarged bore so that a correspondingly larger new pipe can be installed in lieu of the old pipe. In U.S. Pat. No. 4,930,542 by Winkle, et al., there is disclosed an underground pipe restoring technique for pushing new sections of pipe in the path of the old pipe. In the Winkle, et al. system, a frontal part of the apparatus is hydraulically operated to expand radially outwardly and break up the tile. Once the old tile is broken, a hydraulic ram in the back section pushes the new pipe sections forwardly, as well as pushes the frontal section forwardly into the old pipe. The movement of the apparatus is halted and the frontal element is again actuated to expand radially outwardly and break up the old pipe.
In many of the techniques disclosed in the prior art, the pipe bursting element must be pulled by a cable through the old pipe system. The disadvantage of such a technique is that the cable must be initially routed through the old pipe system, which effort can be extremely difficult if the old pipe system is broken and dirt or debris has otherwise fallen into the pipe. Further, an extremely large area must be dug into the soil at the distant end to provide room for pulling equipment, such as a winch. The prior art also includes pipe bursting equipment that is very complicated and expensive and subject to breakage or inoperability when soil or pieces of broken pipe fall into the mechanism.
From the foregoing, it can be seen a need exists for a new technique and apparatus for replacing underground piping systems without disturbing the surface soil and which can be carried out efficiently and reliably. A further need exists for a technique that can be operated in a manhole to replace old deteriorated pipes extending therefrom. Yet another need exists for a technique for replacing old underground pipes with new clay tile or ductile iron sections by pushing the new pipe sections into the path of the old pipe. Another need exists for a lubricant delivery system for efficiently dispensing a lubricant to reduce the skin friction and penetration friction forces encountered in installing the new pipe sections in the path of the old pipe. These and other needs are met by the features and advantages of the invention which are described in detail below.
In accordance with the present invention, various techniques and apparatus are disclosed for replacing old or deteriorated underground pipes with new pipes, in such a manner as to eliminate or reduce the problems heretofore encountered. In accordance with an important feature of the invention, a rear hydraulic jack assembly situated in a manhole or excavated pit is effective to push sections of new pipe and also push a frontal jack assembly to break up the old pipe and form a path or burrow for the sections of the new pipe. The frontal apparatus includes a hydraulic jack that has a backplate adapted for mating directly to the frontal edge configuration of the foremost new pipe section. The frontal jack is situated between the foremost new pipe section and a cone expander to push the cone expander. The movement or pushing force exerted on the cone expander can be exerted by a frontal jack, and thus can be independent of the rear hydraulic jack. In this manner, when the force required of the rear jack is insufficient to push both the string of new pipes as well as the cone expander to break up the old pipe, the rear and the frontal jacking apparatus can be operated independently to sequentially break up the old pipe and form a burrow, and then to advance the new pipe in the burrow.
According to the preferred embodiment of the invention, a frontal arrangement includes a rigid, elongate cylindrical sleeve coupled to the back of a cone expander. The cylindrical sleeve is coupled behind the cone expander so that when the arrangement is pushed forwardly, a straight burrow is formed, even if the original path of the pipe has deviations due to settling or the like. The cone expander can be connected to an elongate snout that is pushed inside the old pipes and provides a directional mechanism for routing the frontal arrangement. Directly behind the snout is a tubular section having fins extending radially outwardly therefrom for either fracturing the old pipes or forming lines of weakness therein. The elongate sleeve, the cone expander and other components pushed in the path of the old pipes can be connected together so as to be disassembled for easy assembly or disassembly in a manhole. When the cone expander is assembled so as to be coupled to the elongate sleeve and the elongate finned member and/or snout as the leading apparatus, the cone expander is forced to maintain a straight or linear path.
The rear jacking system is constructed so that it can be situated in a manhole and utilized to push short sections of new pipe into the path of the old piping system, as well as push the frontal jacking system. This is accomplished by a double-action hydraulic jack that can be coupled to a section of the new pipe in the manhole. The jack is then operated to push the new pipe section in a forward direction into the burrow. When the jack is operated to a fully extended position where the section of new pipe is pushed into the path, the jack is disengaged and coupled to another section of new pipe.
According to an alternate embodiment of the cone expander, there is provided a cone which has an offset axis. This type of cone expander is highly useful for replacing old pipes that are laid adjacent to a rock bed or solid sidewall structure, whereby the old pipe and surrounding soil is expanded in a direction away from the solid rock.
In yet other embodiments of the invention, a lubricant is piped from a surface reservoir through the new pipe sections to the frontal jacking apparatus. The lubricant is forced out of holes in the cone expander to reduce the penetration friction as the cone expander is forced through the old pipe system to break it and expand the surrounding soil, thereby reducing the force required of the jacking apparatus.
The frontal jacking apparatus is also structured so that a lubricant is dispensed through ports to reduce the skin friction of the new pipe sections as they are forced forwardly in the burrow. Intermediate lubricators disposed between new pipe sections can be utilized to further facilitate the reduction of skin friction when the new pipe run is long.
According to yet another embodiment of the invention, multi-part pipe sections having an outer synthetic sidewall and an inner rigid steel pipe, can be utilized for replacement of the old underground pipes. In this embodiment, the rigid steel pipes are used as the mechanism in which the rear jack forces the multi-part pipe sections in the path of the old pipes, and which carry with it the synthetic outer sleeve. When the entire line of multi-part piping system has been installed, the inner rigid pipe is removed, whereby the outside synthetic pipe remains for carrying the waste water or sewage.